Aerosol dispensers, which are widely used in the packaging industry, present two major problems, atmospheric pollution from the propellant and disposal of the cannister without the risk of explosion and the accompanying hazard to personal safety. The use of hand actuated pump dispensers as a substitute for aerosol dispensers obviates these problems.
Typical pump dispensers presently on the market incorporate a manually operable reciprocating pump mechanism as part of a screw-on closure for a container so that the dispenser may be removed from the container for refilling the container. Such dispensers may have a trigger member, plunger or other protruding element which is intended to be moved manually to operate a pump piston in the dispenser, usually against the force of a return spring, so that liquid may be pumped from the container and dispensed through the liquid ejection nozzle or outlet of the device.
To meet consumer demands for convenience it has been found highly desirable that the nozzle be adjustable to provide widely varying discharge patterns, i.e. a spray pattern and a stream pattern. Exemplary of such nozzles are the ones described in U.S. Pat. Nos. 3,843,030, 3,967,765 and 3,685,739. Since it is also highly desirable that the dispensers should have the ability to be attached to the container for shipment, it is mandatory that the dispenser be capable of acting as a liquid-tight closure for the container during shipment. This liquid-tight characteristic should be present even if the container is tipped over on its side and remains in such position for a long period of time. To achieve this characteristic the dispensers disclosed in the above-mentioned patents all have an "Off" position which is designed to close off the nozzle opening to prevent leakage therethrough. However, the consumer is not always that observant and will, on many occasions, leave the nozzle in the "Spray" or "Stream" position which will result in the nozzle being open to leakage should the container be tipped over. Also, it is possible that leakage could occur should the nozzle be inadvertently packaged in a position which places the containers upside down or on their sides.
The answer to this problem is to provide the dispenser with a static seal which is not dependent upon whether or not the dispenser nozzle is in an open or closed position. A highly useful dispenser design which provides such structure is described in U.S. Pat. No. 4,161,288. This structure is capable of providing multiple dispensing patterns and is capable of maintaining a liquid-tight seal at the nozzle irrespective of whether or not the nozzle is adjusted to the open or closed position. This design, however, is not without certain drawbacks. Referring to the disclosure in this patent, it is seen that a flexible nozzle check valve is provided which fits onto the nozzle barrel and closes the pump bore off. Due to the valve design and the fact that the valve is of an elastomeric material, e.g. thermoplastic rubber, the pump bore is sealed off when there is no fluid pressure applied against the nozzle check valve through the pump bore. In this mode the situation is static and no leakage is possible through the bore even should the container be tipped over. To dispense the product the liquid-tight seal made by the nozzle check valve is broken by the force of the fluid being pumped through the bore and against the valve. Since the valve is made of elastomeric material, it is able to expand out in response to such force and allow the fluid to be dispensed. When the fluid pressure is relieved, such as at the end of the pumping stroke, the nozzle check valve can return to its seated position sealing off the pump bore. But because of the necessity of using an elastomeric material for the valve, difficulty is encountered when the product to be dispensed is such that it interacts with the elastomeric material and causes the nozzle valve to lose its elastic quality or to swell. Exemplary of products which have been found to have adverse reactions with elastomeric materials are petroleum distillates, hydrocarbon solvents, etc. Thus, even though the dispenser shown in U.S. Pat. No. 4,161,288 has many advantages and is capable of providing a multipattern dispensing mode and is able to achieve static sealing of the pump bore, it is still incapable of handling materials which react adversely with the nozzle check valve.
Therefore it is an object of the present invention to provide a nozzle system which is usable on manually operated reciprocating dispensing pumps, which has spray and shut-off modes, which is capable of achieving a static seal over the pump bore, and which is capable of handling products not manageable by present-day elastomeric materials.